The Jira Work Management board has a limit of 3000 issues
Platform Notice: Cloud Only - This article only applies to Atlassian products on the cloud platform.
Summary
Jira Work Management board will display the first 3000 issues added to it whereas newly created issues added to the board will not. This limit has been increased from the previous 1000 issues limit.
Environment
Jira Cloud
Jira Work Management Business Company-Managed Project board
Diagnosis
When opening a Jira Work Management Board the will be at least a column with 1000 issues. 
Steps to reproduce this:
Create a new Jira Work Management Blank Project;
Create 1001 issues in the project created in the previous step;
Open the Jira Work Managed Business Project board created in step 1;
We will noticed that the sum of all of the columns will indicate 1000 issues even though there should be 1001 issues
Jira Work Management board’s currently has a limit of 3000 issues.
JWMCLOUD-23 - Getting issue details... STATUS
Solution
Jira Work Management projects includes shortcut options. Therefore, it would be possible to:
1. On the top menu, select Your Work → View All Boards;
2. On the upper right corner select Create Board;
3. Select Create a Board → Board from an existing project;
4. Assign the Board name, select the target Business Project, and use Personal as the Location;
5. Copy the URL of the board created in step 4 and add it to Shortcuts under the project’s Menu Bar
6. As a result, the shortcut will forward to a classic board which has a threshold of 5000 issues, and that can always be adjusted to reduce the overall number of issues pulled into the board, consequently bypassing the board’s threshold issue limit.